Biodegradable deformable thermoplastic materials and packages made thereof

Abstract

PCT No. PCT/DE95/01732 Sec. 371 Date Jun. 6, 1997 Sec. 102(e) Date Jun. 6, 1997 PCT Filed Dec. 6, 1995 PCT Pub. No. WO96/17888 PCT Pub. Date Jun. 13, 1996Biodegradable thermoplastic materials made of blends of starch esters and polyalkylene glycols with additions of polybasic aliphatic carboxylic acids and oxycarboxylic acids are improved with respect to water stability and mechanical characteristics and barrier properties by admixing to the blends aliphatic polycarbonates at levels of from 5:95 to 95:5 with the optional addition of ecologically compatible plasticizers and fillers. These materials can be used for all goods which are to be packaged in films, in particular tobacco products, but also soap, paper tissues, toilet articles, and the like. In addition to biodegradability, said materials are characterized in that they may be fed to a special recycling process, but also to conventional recycling processes without adversely affecting them.

We claim: 
     
       1. A biodegradable thermoplastic deformable material comprising a blend of starch esters based on starch with an amylopectin content of from 20% to 80% by weight as well as a degree of substitution of from 1.5 to less than 3 with polyalkylene glycol or a mixture of different polyalkylene glycols having molecular weights of from 200 to 2,000 g/mol in a mixture ratio of starch esters to polyalkylene glycol of 10:1 to 10:5 parts by weight, wherein said blend is compounded with an aliphatic polycarbonate of the formula ##STR2## with R1, R2=hydrogen or straight or branched chain alkyl groups with 1 to 4 C atoms and wherein n equals from about 250 to 10,000 in a ratio of 95:5 to 5:95, a 0 to 30% biodegradable plasticizer and a 0-35% filler based on the total mass.   
     
     
       2. The biodegradable thermoplastic deformable material of claim 1, wherein the aliphatic polycarbonate is contained in a mixture ratio of 30:70 to 70:30 in the blend. 
     
     
       3. The biodegradable thermoplastic deformable material of claim 1, wherein the plasticizer is an ester of phthalic acid with a C 1  -C 10  n-alkanol. 
     
     
       4. The biodegradable thermoplastic deformable material of claim 1, wherein the biodegradable plasticizer is a member selected from the group consisting of a polyethylene glycol, a monoester from polyethylene glycol with a C 1  to C 10  carboxylic acid and a diester from polyethylene glycol with a C 1  to C 10  dicarboxylic acid and mixtures thereof. 
     
     
       5. The biodegradable thermoplastic deformable material of claim 1, wherein the aliphatic polycarbontae is polypropylene carbonate. 
     
     
       6. The biodegradable thermoplastic deformable material of claim 1, wherein the aliphatic carbonate is polyethylene carbonate. 
     
     
       7. The biodegradable thermoplastic deformable material of claim 1, wherein aliphatic polycarbonate is a polyalkylene copolymer or a polyalkylene terpolymer. 
     
     
       8. The biodegradable thermoplastic deformable material of claim 1, wherein the starch ester is starch acetate. 
     
     
       9. The biodegradable thermoplastic deformable material of claim 1, wherein the starch ester has a degree of substitution of between 1.5 and 2.5 
     
     
       10. The biodegradable thermoplastic deformable material of claim 1, wherein the aliphatic polycarbonate has a degree of polymerization of 200-5,000. 
     
     
       11. A packaging method comprising blending a blend of starch esters based on starch with an amylopectin content of from 20% to 80% by weight as well as a degree of substitution of from 1.5 to less than 3 with polyalkylene glycol or a mixture of different polyalkylene glycols having molecular weights of from 200 to 2,000 g/mol in a mixture ratio of starch esters to polyalkylene glycol of 10:1 to 10:5 parts by weight for forming a blend; compounding said blend with an aliphatic polycarbonate of the formula ##STR3## with R1, R2=hydrogen or straight or branched chain alkyl groups with 1 to 4 C atoms and wherein n equals from about 250 to 10,000 in a ratio of 95:5 to 5:95, a 0 to 30% biodegradable plasticizer and a 0-35% filler based on the total mass and thereby obtaining a biodegradable thermoplastic deformable material; forming the biodegradable thermoplastic deformable material for packaging purposes;   packaging goods with the formed biodegradable thermoplastic deformable material.   
     
     
       12. The packaging method according to claim 11 wherein the goods are a member selected of the group consisting of food, cosmetics, detergent, paper tissues and toilet articles. 
     
     
       13. A package made of a biodegradable thermoplastic material comprising a blend of starch esters based on starch with an amylopectin content of from 20% to 80% by weight as well as a degree of substitution of from 1.5 to less than 3 with polyalkylene glycol or a mixture of different polyalkylene glycols having molecular weights of from 200 to 2,000 g/mol in a mixture ratio of starch esters to poyalkylene glycol of 10:1 to 10:5 parts by weight, wherein said blend is compounded with an aliphatic polycarbonate of the formula ##STR4## with R1, R2=hydrogen or straight or branched chain alkyl groups with 1 to 4 C atoms and wherein n equals from about 250 to 10,000 in a ratio of 95:5 to 5:95, a 0 to 30% biodegradable plasticizer and a 0-35% filler based on the total mass, and   wherein said biodegradable thermoplastic deformable materials are foils, coatings or combined materials.   
     
     
       14. The package according to claim 13 wherein said package consists of one layer. 
     
     
       15. The package according to claim 13 wherein said package is a member selected from the group consisting of refillable packages, sales packages, repackaging, transport packages or components of the same. 
     
     
       16. The biodegradable thermoplastic deformable material of claim 1, wherein the degree of substitution is from 1.8 to 2.4. 
     
     
       17. The biodegradable thermoplastic deformable material of claim 1, wherein the blend contains an aliphatic saturated and/or unsaturated dicarboxylic acid and/or a hydroxycarboxylic acid, a hydroxydicarboxylic acid, or a hydroxytricarboxylic acid, with 2 to 10 C atoms in a mixture ratio of blend to acid of 100:2 to 1,000:1 parts by weight.   
     
     
       18. The biodegradable thermoplastic deformable material of claim 17, wherein the hydroxycarboxylic acid, the hydroxydicarboxylic acid, or the hydroxytricarboxylic acid is a tartaric acid or citric acid.   
     
     
       19. The biodegradable thermoplastic deformable material of claim 4, wherein the biodegradable plasticizer is a member selected from the group consisting of triethylene glycol diacetate, a glycerine triacetate and a citric acid trialkyl ester.